1. Field of the Invention
The present invention relates to a process for producing a cracked distillate and hydrogen from a heavy oil.
2. Description of the Prior Art
The present inventors previously invented a process which comprises catalytically cracking a heavy oil (e.g., atmospheric residual oil, vacuum residual oil, etc.) in the presence of a nickel ore, by which heavy metals contained in the heavy oil are removed and the heavy oil is cracked (see Japanese Patent Application (OPI) No. 10202/74). However, it has been found that if the above-described heavy oil is subjected to catalytic cracking in the presence of laterite or a laterite-containing catalyst (hereinafter, both are referred to as laterite catalysts), coke is formed on the laterite catalyst as the heavy oil is cracked to a distillate oil, and when the laterite catalyst on which the coke is deposited is heated in a gas stream, the iron oxides in the laterite catalyst are very rapidly reduced and hydrogen is easily formed by bringing the reduced catalyst into contact with steam.
Hitherto, a process has been proposed for producing gaseous hydrocarbons and a hydrogen-rich gas which comprises catalytically cracking a heavy oil in the presence of a catalyst which carries an oxide of a metal such as nickel or vanadium on bauxite to crack the heavy oil and to deposit coke on the catalyst, and contacting the catalyst on which coke is deposited with steam (see Japanese Patent Publication No. 30596/75 and U.S. Pat. No. 3,726,791). However, in this process, the catalyst is a so-called synthetic catalyst and contains components which deteriorate at high temperatures such as alumina, and deterioration of the catalyst is unavoidable upon reaction at high temperatures. Further, in this process, since the catalyst on which the coke is deposited is brought into contact with steam, the hydrogen concentration in the gas from a gasification zone does not become high because carbon monoxide and carbon dioxide are generated by the reaction of coke and steam.
In addition, a process for the production of hydrogen using metalliferrous steam reducing agent-containing particles has been proposed (see U.S. Pat. No. 3,017,250). However, in this process the catalyst is a synthetic catalyst similar to the above-described patents, and the reaction system employed therein comprises four zones, i.e., a coking zone, a heating zone, a regeneration zone and a reaction zone, and a cracked gas is used as the reducing gas. As described above, since in U.S. Pat. No. 3,017,250 the heating (exothermic) and regeneration (endothermic) are individually performed, the step for circulating the catalyst is complicated, and further, since the exothermic zone and endothermic zone are individually provided, the amount of the catalyst which is circulated in the system increases, leading to an increase of attrition of the catalyst.